Just 1.25W per centimeter of 32 gauge wire?! It's gonna melt really fast =\ If you need power heating element wire why not use an old toaster or the heating element from a hair drier? Should have more than enough power.. Mr RB's solution seems pretty straight forward and easy to scale up as high as you want. If you're worried about radiated heat from the bulbs put a heat shield in front of the bulbs and blow air across them to circulate in the incubation chamber. For reliable heating control you'll want some kind of forced air anyways.

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The data sheets for nichrome wire indicate that there is a hot ohm specification, as well as a cold ohm spec. Difficult to say what your data is for, without more detail.

It would be worth a try to get some clips, or maybe some crimp type terminal connectors, and see if 120 V and a 6 foot length or your wire would provide a usable heat source .... without any significant problems.

One thing you would want to do is to physically stabilize the nichrome wire when it is in place.
Find some ceramic knobs, or something similar. You could zig-zag the wire, or arrange it in a suitable pattern in front of the ventilation fan, and not worry about it getting out of shape. Ceramic knobs with spikes were available at hardware stores ... and were used for electrical purposes, at one time. Any type of is ceramic insulator might be useful as a support.

Another thought .... If you are not going to be physically lifting your incubator, you could allow for some additional interior volume at the bottom of the unit, and install some extra thermal mass.
Thermal mass might consist of 50 or 100 lbs of ceramic tiles. Rock salt might work as well.
It depends on how much cleaning/sanitizing ... convenience factor ... is going to be required. The extra thermal mass would attenuate .... decrease ... adverse thermal effects that result from opening the access door.
With extra thermal mass, the start up period would be extended until the operating temperature is attained.

 

user 88, I'm not sure you understand how little mass there is in 32 gauge wire over a 1 centimeter length, 1 watt is WAY too much. All the heaters I've taken apart are made from spiral wound wire, or ribbons such as in a toaster oven. Ribbons works well because of their high surface area.

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ok, i hooked up the nichrome wire and 8 feet seems to put off plenty of heat at 70 watts. problem is when its heated it expanded a lot, to much actually. they will almost touch. i tried tightening the wire to the isolators when it was electrified then when i removed the heat , Snap, it broke. Does ne1 know of a source where i can buy the type of Resistance wire found in space heaters, hair driers, etc. the coil type about 18 gauge it looks like? i want to buy by the foot.

 

I hate to state the obvious, but why don't you buy a hair dryer or use an old toaster? The wire is there, it's designed to and obviously already runs off mains AC power and produces 1000 watts or so of heat!

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Remember that Hair dryer resistance needs an airflow to avoid overheating and burning up. The toaster is a magnificent idea, or the light bulbs

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Felipe

 

Hopefully the o.p. will come back with a report on his experiment with the 32 gauge wire.
It is difficult to be certain that everybody is on the same page. That is, talking about the correct material .... units ... dimensions ....

His resistance measurement corresponds to the Nichrome A material ... @ 32 AWG.

No ... not actually sure it will work at this point.

 

Menticol, a thermal monitor loop already has to be in place just put it near the heating element, with a thermal fuse for safety, that's all hairdryer makers do, and my idea was to use AC dimming to adjust the heating of the heating element whatever it ends up being. The fan should always be running.

user88, 1.2 watts per centimeter of 32 gauge wire. It will melt unless it is extremely well coupled to something that's cooling it. IE not air, since it's a resistance heating element it can't be wrapped around a metal heat pipe..

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Do they ensure viability of the eggs ?

 

Hi cbiblis,

I do not recommend to use radiation heat in an incubator. Depending on the relative position between heaters and eggs the eggs being closest to the heater will fry.

Use a normal household heater (like in a toaster) and blow circulating air over the heating element to distribute it using guides.

For the air intake use an adjustable sliding door to mix internal air with fresh air.
(Just using internal air the eggs rot before hatch.)

Boncuk

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Proper Planning Prevents Piss Poor Performance

 

thanks for the reply all. What I'm looking for is the wire in a hair dryer. i am mass producing incubators, so i don't want to waste money on a hairdryer just to get the wire out of it. i would like to by about 100' of it and cut it to size for my application. i have yet to come across a site where they sell it by the foot so if anyone knows where i can purchase it let me know.

 

Resistance Wire.Com | Nickel Chrome, Nickel Copper, and Iron Chrome Aluminum Alloys from Stock

 

Thanks. I've built a few incubators over the years. Light bulbs are good because when you open the door to inspect, the temp drops a couple degress and the bulbs come on full so you can see what you are doing.

Also you get to keep the wiring up high so the thing can be cleaned, etc, especially with eggs which are very conductive (and horrible to clean up once they dry). The last thing I would suggest is heating wire under the egg tray. Keep the bottom half of the thing totally free from wiring so you can clean and/or slide trays out etc. Put some light bulbs in the top in standard light sockets with a 4" 120v PC fan (the old style). Even a little fan will circulate the air well and give even heating. You can change and inspect heaters by just unplugging the light bulbs, or even reduce number of bulbs or change bulb wattages etc. Who wants to mess with fine heater wire and mains voltages??

 

The 8' length of 32 AWG allowed too much current to flow, @ 120 V.
You might try a longer length of 32 AWG wire. Maybe a 12' length would add a sufficient amount of resistance, in order to reduce the current, and energy density, to the point that a critical temperature in the nichrome wire would be avoided.

Note that reducing the current by 1/2 causes a 1/4 reduction in electrical power. ...(P=I²R).

The previous statement is incorrect. If the original power was P=I²R, and you then decreased the current by doubling the resistance, then the new power would be
P=(½I)²(2R)=½I²R
That is, the power would be reduced by ½, not ¼.

 

It's still gonna spring all over the place from thermal expansion, even with the reduced heat. I'm not sure why they'd even sell 32 gauge nichrome wire except for perhaps using in e-matches.

Where did you purchase your nichrome wire from, and do they have a wider slection of material types?

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